Process for making oxazolidones



United States Patent 7 3,168,525 PROCESS FOR MAKTNG OXAZOLIDONES Manuel M. Baizer, Dayton, Ohio, assignor to S. B. Penick and Company, New York, N .Y., a corporation of Delaware No Drawing. Filed Apr. 25, 1960, Ser. No. 24,250

8 Claims; (Cl. 260-307) The present invention relates to processes involving the seriatim acylation and cyclization of substituted carbamyloxy propanes to form substituted oxazolidones.

The class of compounds identified as S-(substitutedmethyl)-2-oxazolidones, with a wide variety of 5-substituent organic radicals, is known in the, art as a group of substances useful per se and as intermediates for making R--CH CH(OH) CH NH amino-alcohols and their corresponding beta-halo amines by known procedures.

It has for some time been known to produce N-substituted oxazolidones by the cyclization in the presence of base of N-su'bstituted-1:halo-2-carbamyloxy alkanes.

This process is not applicable to the production of oxazolidine ring is unsubstituted, as pointed out by Jones,

J. Chem. Soc., 1957, page 2735. Thus, the oxazolidones prepared from halocarbamates by procedures known in the art cannot be used to prepare ethanolamines in which the amino group is a primary amino group.

According to this invention, it is now possible to pro duce N-unsubstituted-5-substituted-methyl-Z-oxazolidones from N-unsubstituted'1-halo-2-carbamyloxy-3substituted propanes.

The present invention resides in the concept of making certain S-(substituted-methyl)-2-oxazolidones, by reacting a 1-halo-2-carbamyloxy-3-substituted propane with an acylating agent to produce a l-halo- Z-(N-acyl-carbamyloxy)-2-substituted propane and cycylizing said propane. Any substance commonly employed as an acylating agent can be used in the process, although agents having from one to ten carbon atoms in the acyl moiety are preferred because of present availability and economy. All four halogens are equivalent in'the process and the cyclic organic radical can be an aryloxy or arylthio radical of the benzene and naphthalene ether series, whether unsubstituted or substituted by one or more low molecular weight moieties such as lower-alkyl, lower-alkoxy, halo, nitro, amino and tri fluoromethyl. It is seen that the nature of the 3-substituent on the starting propane determines the nature of the S-substituent in the oxazolidone prepared by the instant process.

In carrying out the acylation step of the process, the lhalo-2carbamyloxy-3substituted propane is mixed with an acylating agent and, desirably an acid catalyst. The mixture is heated, preferably on a steam bath and then under reflux until the reaction is substantially complete and the 1-halo-2-(N-acyl-carbamyloxy)-3-substituted propane is recovered from the crude reaction product, or employed directly without purification or recovery, as the starting material following cyclization step. Among the acid catalysts which can be used are mineral acids as sulfuric, hydrochloric; organic acids as p-toluene-sulfonic; and other Lewis acids commonly known by chemists to promote acylation of the amino group. The acylating agents of choice are the lower alkanoic acid chlorides and anhydri des.

In carrying out the cyclization step of the process, the 1-halo-2-(N-acyl-carbamyloxy)-3-substituted propane can be cyclized directly to yield the final product, a S-substituted-methyl-2-oxazolidone by reaction with a strong alkali, such as sodium hydroxide, potassium hydroxide, et cetera, at a temperature ranging from room temperature to about 70 or 80 degrees centrigrade. Care must be 3,108,525 Patented Feb. 2, 1965 taken to avoid maintaining the reaction mixture too long at the elevated temperature, to avoid decomposition of the '5-substituted-methyl-2-oxazolidone.

Alternatively, the cyclization step of the process can be carried out by reacting amild alkali, such as sodium carbonate, potassium carbonate, or ammonium hydroxide, with the 1-halo-2-(N-acyl-carbamyloxy)-3-substituted propane to obtain a mixture of the final product, the 5- substituted-methyl-Z-oxazolidone and an intermediate 5- substituted-methyl-3-acy1-2-oxazolidone. The intermediate 5-substituted-methyl-3-acyl-2-oxazolidone can be separated from the final product and separately hydrolyzed with alkali to produce an additional quantity of the final product, the 5-substituted-methyl 2-oxazolidone.

The starting materials for conducting the process of the invention, that is, the 1-halo-2 carbarnyloxy-3-substituted propanes can be prepared as follows: The appropriate 3-substituted-1,2-propanediol is condensed with a carbonic acid ester (R CO to form the corresponding 4- -substituted-2-dioxolone. Processes for carrying out this reaction are disclosed, for example, in United States Patents 2,770,649 and 2,813,104. Next, the 4-substituted-2- dioxolone is ammonolyzedwith ammonia in a solvent to yielda mixture of two isomers. a 1-hydroxy-2carbamyloxy-S-substitirted propane and a l-carbamyloxy-Z-hydroxy-3-substituted propane. 'This mixture results because the dioxolone ring opens at different positions upon ammonolysis. The isomers can be separated by fractional crystallization. The procedures for carrying out this ammonolysis are disclosed in Baizer et al. in the Journal of Organic Chemistry, volume 22, pages 1595 to 1599 (1957).

Where a l-chloro-2-carbamyloxy-3-substituted propane is desired as the starting material for the process of the invention, the isomeric mixture, obtained as outlined in the previous paragraph, can, without separation of isomers, be treated with thionyl chloride to produce chlorination of the 1-hydroxy-2-carbamyloxy-propane and both chlorination and rearrangement of the 1-carbamyloxy-2- hydroxy-propane and yield the l-chloro-Z-carbamyloxypropane. Procedures for carrying out this process are also disclosed in the above-mentioned Baizer et al. paper.

Throughout the specification, where the word percen is used alone, this means percent by weight. a The following examples illustrate physical embodiments of the inventive concepts:

Example 1.-C0nversi0n of 1-chlor0-2-carbamyloxy-3- (o methoxyphenoxy) propane to S-(O-methoxyphenoxymethylJ-Z-oxazolidone Prepare the starting material, 1-chloro-2-carbamyloxy- 3-,(o-methoxyphenoxy)propane as follows:

Melt 99 grams of 1,2-dihydroxy-3-(o-methoxyphenoxy)propane. Add 1.4 grams of sodium .methoxide and 118 grams of dry diethyl carbonate to the melt. Distill out the ethanol formed by the ester interchange reac tion until the inside temperature of the reaction mixture reaches 120 degrees centigrade. Then add 1.5 grams of ammonium chloride and recover the excess diethyl carbonate by vacuum distillation. The residue contains 4- (o-methoxyphenoxymethyl(dioxolone melting at 68.4- 69.0 degrees centigrade. While stirring, add milliliters of isopropyl alcohol to the residue. Next add a solution of 17 grams of ammonia gas in 500 milliliters of isopropyl alcohol. Close the system'and continue stirring overnight. Thereafter, distill the mixture in vacuo to remove gas and isopropyl alcohol. To remove the last traces of isopropyl alcohol, add toluene to the residue and complete the removal of solvent by distillation, leaving a residue. Add 400 milliliters of toluene to dissolve the residue. Next add 65 grams of thioyl chloride to the solution. Warm the mixtureto 50 degrees centigrade and commence bubbling dry air through the mixture to sweep out gases. While continuing the bubbling of air, raise the temperature to 80-85 degrees centigrade and maintain it there for two hours. Remove part of the'toluene by distillation. Cool the solution with the formation of a precipitate. Filter the precipitate. Concentrate the filtrate by removing toluene by distillation. Cool the concentrated filtrate With the resultant formation of a second precipitate. Filter the second precipitate and combine it with the first precipitate to obtain a total of 104.5 grams of 1-chloro-2-carbamyloxy-3-(omethoxyphenoxy)propane, (80.7 percent yield).

Carry out the acylation and cyclization of the invention as follows: Mix one part of l-chloro-Z-carbamyloxy- 3-(o methoxyphenoxy)propane, prepared above, with a molar excess of acetic anhydride and a catalytic quantity of p-toluenesulfonic acid. Heat the mixture on a steam bath for one hour. Thereafter, while heating the mixture to maintain it under reflux, add alcohol. The mixture dissolves in the alcohol. Next, while maintain ing the solution at about 70 degrees centigrade, add sodium hydroxide. A precipitate forms shortly after the completion of the addition of the sodium hydroxide. Stir and cool the mixture for one hour. Filter and dry the precipitate to obtain 5-(o-methoxyphenoxymethyl)- 2-oxazolidone melting 140-145 degrees centigrade.

Example 2.--Preparatin 0f (0 methoxyphenoxymethyl 2 oxazolidine with isolation of the intermediate 1 chloro 2 (N-acetylcarbamyloxy) 3 (0- methoxyphenoxy) propane.

Dissolve. 5 grams of l-chloro-2-carbamyloxy-3-(omethoxyphenoxy) propane and 0.2 grams of p-toluenesulfonic acid in 40 milliliters of acetic anhydride. Heat the solution on a steam bath for one hour. Remove the excess acetic anhydride by evaporation in vacuo. Add 5 milliliters of methanol to the residual solution remaining after removal of the excess acetic anhydride. Evaporate the solution to dryness, leaving a residue. Dissolve the residue in hot methanol. Cool the solution with resultant precipitation. Filter and dry the first crop of solid precipitate weighing 4.3 grams and melting at 110.0- 111.5 degrees centigrade. Evaporate methanol from the filtrate to concentrate the solution. Cool the solution with resultant precipitaion of a second crop of product. Filter and dry the second crop of solid precipitate weighing 0.6 grams and melting at 109.0-110.5 degrees centigrade. Evaporate methanol from the filtrate to concentrate the solution. Cool the solution with resultant precipitation of a third crop of product. Filter and dry the third crop of solid product weighing 0.7 grams and melting at 90-95 degrees centigrade. Combine the first, second and third crops into 5.6 grams of crude l-chloro- 2 (N-acetylcarbamyloxy) 3 (o-methoxyphenoxy)- propane. Recrystallize a sample for analysis from ethanol ,solvent and obtain an analytical sample melting at 111.0-

1115 degrees centigrade.

Analysis of the sample is as follows:

Percent Percent Percent Carbon Hydrogen Chlorine Calculated 51. 74 5. 35 11.75 Found 52. 75 5. 61 11. 7

cipitate to recover 1.85 grams of crude 5-(o-methoxyphenoxymethyl)-2-oxazolidone, melting at 137-139 degrees centigrade. Recrystallize samples from ethanol solvent to produce purer portions melting at 140-145 degrees centigrade.

Example 3.-Preparati0n of 5-(o-meth0xyphen0xymethyl)-2-0xaz0lid0ne from 1 chloro 2 carbamyloxy- 3-(0-meth0xyphen0xy propane Dissolve 20.76 grams of 1-chloro-2-carbamyloxy-3-(omethoxyphenoxy)propane and 0.4 gram of p-toluenesultonic acid in 9 grams of acetic anhydride. Heat the solution for one hour at 100-110 degrees centigrade, to form a molten mass. Cool 199 milliliters of an aqueous solution of 1.285 normal sodium hydroxide to about 14 degrees centigrade. While stirring the aqueous solution, pour the molten mass into the solution. Five minutes after the pouring is complete, crystals begin precipitating. Stir the mixture for one hour at room temperature and then filter to recover 13.3 grams (74.5 percent yield) of crude 5-(o-methoxyphenoxymethyl)-2-oxazolidone, melting at 136-139 degrees centigrade. Recrystallize to get product melting 140-145 degrees centigrade.

Example 4.Preparation of 5-(0-meth0xyphenoxymethyl) 2 oxazolidone from a mixture of J-hydroxy-Z- carbamyloxy 3 (0 meth0xyphen0xy)pr0pane and 1 carbamyloxy 2 hydroxy 3 (0 meflmxyphenoxy propane Mix 8.435 grams of 1-carbamyloxy-2-hydroxy-3- (o-methoxyphenoxy)propane and 3.615 grams or" l-hydroxy 2-carbamyloxy-3-(o-methoxyphenoxy)propane in 50 milliliters of toluene at 25 degress centigrade. Add 6.5 grams of thionyl chloride to the mixture. Warm the mixture to about 50 degrees centigrade and commence bubbling dry air through the mixture to sweep out gases. While continuing to bubble air, raise the temperature of the mixture to about degrees centigrade and maintain this temperature for two hours. Thereafter, remove the toluene by distillation, leaving a residue. To the residue, add 5.6 grams of acetic anhydride and 0.1 grams of p-toluenesulfonic acid. Heat the mixture on a steam bath for one hour. Thereafter, while maintaining the mixture under reflux, add 20 milliliters of ethanol into which the mixture dissolves. Next, While maintaining the mixture at a temperature of 70 degrees centigrade, add 130 milliliters of sodium hydroxide thereto. Precipitation of a solid begins shortly after the addition of sodium hy droxide is completed. Stir and cool the mixture for one hour. Filter the mixture to recover 8.0 grams of solid crude 5-(o-methoxyphenoxymethyl)-2-oxazolidone, melting at 137-140 degrees centigrade.

Example 5 .-Pr0d uction o f intermediate 1 -chl0r0-2- (N acetylcarbamyloxy) -3-( o-chlorophenoxy propane and 5 o-ch lorophenoxymethyl -2-0xaz0 lidone Prepare the starting material, 1-chloro-2-carbamyloxy- 3-(o-chlorophenoxy) propane, as follows:

Add 202.5 grams (1 mole) of 3-(o-chlorophenoxy)-1,2- propanediol to a reaction flask. Heat the flask to degrees centigrade to melt the diol. Add 2.8 grams of sodium methylate to the molten diol. Add 236 grams (2 moles) of diethyl carbonate to the mixture. Heat the mixture to-distill off the alcohol formed by the reaction through a fractionating column. After the theoretical quantity of alcohol has distilled off, add 3.0 grams of ammonium chloride to the mixture to destroy the sodium methylate catalyst and arrest further reaction. Distill oil" the excess diethyl carbonate under reduced pressure. Remove a sample of the material for analysis of the cyclic carbonate. Crystallize the sample twice from anhydrous isopropyl alcohol to obtain 4-(o-chlorophenoxyrrrethyl) dioxolone melting at 109.0-1093 degrees centigrade and having the following percentage analysis; based on an empirical formula of C H O Cl:

Carbon Hydrogen Calculated 52. 52 3. 93 Found 53. 3. 96

Next, the 4-(o-chlorophenoxymethyl)dioxolone is am- 7 obtain several further crops of crude l-carbamyloxy-Z- hydroxy-3-(o-chlorophenoxy)propane. After several concentrations, evaporate the filtrate to dryness. Fractionally crystallize the residue remaining after evaporation from ethyl acetate solvent to obtain crystalline l-hydroxy- 2-carbamyloxy-3-(o-chlorophenoxy)propane. The total crystalline product obtained is 230 grams (94 percent yield).

The pure 1-carbamyloxy-2-hydroxy-3-(o-chlorophenoxy)propane melts at 98.4-98.9 degrees centigrade and has the following percentage analysis; based .on an empirical formula of C H O ClN:

Carbon Hydrogen Nitrogen Calculated 48. a7 4. a2 5. 70 Found 99 5. 16 5. 74:

The pure 1-hydroxy-2-carbamyloxy-3-(o-chlorophen- 0xy)propane melts at 123 .2-123.5 degrees centigrade and has the following percentage analysis, based on an empirical formula of C H O ClN:

Carbon Hydrogen Nitrogen Calculated 48. 87 4. 92 5. 70 Found 49. 49 5. 01 6. 07

Carbon Hydro- Nitrogen gen Calculated 45. 45 4. 17 5. 30 Found 45. 72 4.35 5. 48

Acylate and cyclize the l-chl0ro-2-carbamyloxy-3-(ochlorophenoxy) propane as follows:

Mix 5.28 grams (0.02 mole) of the l-chloro-Z-carban1yloxy-3-(o-chlorophen0xy)propane with 0.03 gram of zinc chloride and 2.3 grams of acetic anhydride in a reaction flask. Place an oil bath around the reaction .6 flask; Heat the oil bath to a temperature of 100-120 degrees centigrade for three hours. A' hard paste forms in the reaction flask. Crystallize the paste from a solvent mixture of ethanol and water to obtain crystals melting at 66.5-69.0 degrees centigrade. Recrystallize from pentane solvent to obtain 1-chloro-2-(N-acetylcarbamyloxy)- 3-(o-chlorophenoxy)propane melting at 69.7-70.2 degrees centigrade, having the following percentage ,analysis, based on an empirical formula of C H Cl NO Carbon Hydro- Nitrogen gen Calculated 47. 08 4. 38 4. 57 Found 46. 80 4. 00 4.61

Treat the 1 chloro 2 (N acetylcarbamyloxy)-3-(ochlorophenoxy) propane with 10 percent aqueous sodium hydroxide solution to obtain a clear solution in which a precipitate soon forms at a pH of 11.0. Filter the crystalline product (about percent yield). Recrystallize the product from ethyl acetate solvent to obtain 5-(2-chlorophenoxymethyl)-2-oxazolidone melting at 150.5-1508 degrees centigrade. A melting point of 151 degrees centigrade for this compound was found by Beasley et al., Quarterly Journal of Pharmacy and Pharmacology, London, volume IX, page 13.

Example 6.Pr0ducti0m 0 intermediate 1-chl0r0-2-(N- acetylcarbamyloxy)-3-(0-methylphen0xy) propane and 5- o-m cthylplzenoxymethyl) -2-0xa20lidone Prepare the starting material, 1-chloro-2-carbamyloxy- 3-(o methylphenoxy)propane, as follows: React diethyl carbonate with 3-(o-methylphenoxy)-1,2-propanediol to produce 4-(o-methylphenoxymethyl)-2-diox0lone, melting at 95.4-96.0 degrees Centigrade. See Ludwig et al., Journal of the American Chemical Society, volume 73, page 5894. Then ammonolyze the 4-(o-methylphenoxymethyl)-2-dioxolone with ammonia to produce a mixture of 1 hydroxy-2-carbamyloxy3-(o methylphenoxy)propane melting at 115 .0-1 15 .6 degrees centigrade and l-carbamyloxy-2-hydroxy-3-(o-methylphenoxy)propane melting at 92.0-93.0 degrees centigrade. The latter compound was prepared by Yale et al., Journal of the American Chemical Society, volume 72, page 3715. Separate the isomers by fractional crystallization.

Mix one part by Weight of the l-carbamyloxy-Z-hydroxy-3-(o-methylphenoxy)propane with a molar excess of thionyl chloride in-toluene solvent. Heat the mixture to reflux and continue heating until the evolution of hydrogen chloride and sulfur dioxide gases ceases. Bubble dry air through the reaction mixture to sweep out the gases. Cool the mixture and recover, using procedures as set forth in the previous examples, l-chloro-Z-carbamyloxy-3-(o-methylphenoxy)propane, melting at 87.2- 8-8.0 degrees centigrade and having the following percentage analysis, based on an empirical formula of C11H14C1NO3: I

Carbon Hydro- Nitrogen Chlorine gen Calculated 54. 31 5. 79 5. 14. 55 Found 54. 36 6. 04 5. 68 14. 30

Acylate the 1-chloro-2-carbamyloXy-3-(o-methylphenoxy)propane as follows: Mix one part of the l-chloro- 2-carbamyloxy-3-(o-methylphenoxy) propane with a molar excess of acetic anhydride and a quantity of zinc chloride. Heat the mixture for several hours; Recover 1 chloro 2 (N acetyl carbamyloxy) 3 (o-methylphenoxy)propane, melting at 93.5-94.5 degrees centigrade, and having 5.02 percent nitrogen (calculated analysis based on an empirical formula of C H CINQ; is 4.90 percent).

Cyclize the 1 chloro-2-(N-acetylcarbamyloxy-3:(o

methylphenoxy) propane with 10 percent aqueous sodium hydroxide solution to obtain 5-(o-methylphenoxymethyl)- 2-oxazolidone, melting at 1255-1265 degrees centigrade. Beasley et al Quarterly Journal of Pharmacy and Pharmacology, London, volume IX, page 13, report a melting point of 127 degrees centigrade for this compound.

Example 7.-Prducti0n of intermediate l-chloro-Z-(N- acetylcarbamyloxy)-3-(2-naphthyl0xy) propane and (2-naphthyl0xymethyl)-2-0xaz0lid0ne Prepare the starting material, 1-chloro-2-carbamyloxy- 3-(2-naphthyl0xy)propane as follows: React diethyl carbonate with 3-(2-naphthy1oxy)-l,2-propanediol, in a manner similar to that set forth in the preceding examples, to produce 4-(2-naphthyloxymethyl)-2-dioxolone, melting at 1270-1275 degrees centigrade. Then ammonolyze this 4-(2-naphthyloxymethyl)-2-dioxolone with ammonia to produce a mixture of l-hydroxy-2-carbamyloxy-3-(2- naphthyloxy) propane melting at 150.8-151.0 degrees centlgrade and 1-carbamyloxy-2-hydroxy-3-(Z-naphthyloxy) propane melting at 144.5-l45.0 degrees centigrade. Separate the isomers by fractional crystallization.

Mix one part by Weight of the l-carbamyloxy-Z-hydroxy-3-(2-naphthyloxy)propane with a molar excess of thionyl chloride in toluene solvent. Heat the mixture to reflux and continue heating until the evolution of hydrogen chloride and sulfur dioxide gases ceases. Bubble dryair through the reaction mixture to sweep out the gases. Cool the mixture and recover using procedures as set forth in the previous examples, 1-chloro-2-carbamyloxy-3-(2-naphthyloxy) propane melting at 125.5- 126.0 degrees Centigrade having the following percentage analysis, based on an empirical formula of C H ClNO Carbon Hydro- Nitrogen Chlorine gen Calculated 60. 11 5,05 5. 01 12. 67 FOIllld 60. 05 5. 01 4. 45 12. 05

Carbon Hydrogen Nitrogen Calculated 59. 72 5. 01 4. 35 Found 60. ()2 5. 22 4. 50

To cyclize, dissolve the l-chloro-2-(N-acetylcarbamyloxy)-3-(2-naphthyloxy)propane in acetone and treat the solution with percent aqueous sodium hydroxide solution to obtain S-(Z-naphthyloxymethyl)-2-oxazolidone, melting at l93.2-l93.6 degrees centigrade and having the following percentage analysis, based on an empirical formula of C H NO Carbon Hydrogen Nitrogen l ted 69.12 5.38 5.75 gifh d? 69. 28 5. 27 5. 45

Example 8.Pr0ducti0n of intermediate 1 -chl0r0-2- (N pr0pi0nylcarbamyl0xy-3-(Z-naphthyloxy)propane and 5 -2 (-naphthyl0xymethyl -2-oxaz0li done Mix 5.59 grams (0.02 moles) of 1-chloro-2-carbamyloxy-3-(2-naphthyloxy)propane with 3.25 grams (0.025 moles) of propionic anhydride and 0.15 grams of p- Carbon Hydrogen Nitrogen Calculated 60. 81 5. 40 4. 17 Found 60. 29 5. 48 4. 03

Dissolve the 1-chloro-2-(N-propionylcarbamyloxy)-3- (Z-naphthyloxy) propane in acetone and treat the solution with dilute sodium hydroxide. Recrystallize the product obtained from the ethanol solvent to obtain 5-(2-naphthyloxymethyl)-2--oxazolidone, melting at l93.0-193.6 degrees centigrade.

The invention can be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The foregoing physical embodiments are therefore to be considered in all respects illustrative and not restrictive. The scope of the invention is indicated by the subjoined claims rather than by the foregoing description. All changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

Having described my invention, I claim:

1. A process for preparing a S-Substituted-methyl-Z- oxazolidone having a hydrogen atom attached to the nitrogen atom of the oxazolidine ring, wherein the 5sub stituent is selected from the group consisting of phenoxy, lower-alkylphenoxy, lower-alkoxyphenoxy, halophenoxy and naphthyloxy, which includes the steps: reacting with an acylating agent selected from the group consisting of lower-alkanoic acid chlorides and anhydrides, a 3-substituted-1-chloro-2-carbamyloxy-propane whose carbamyl nitrogen atom is unsubstituted, wherein the 3-substituent corresponds to the aforesaid 5-substituent, to produce the corresponding 3-substituted-l-chloro-2-(N-acylcarbamyloxy) -propane; and treating said acylcarbamyloxy-propane with an alkali metal hydroxide to yield the aforesaid 5- substituted-methyl-Z-oxazolidone.

2. A process according to claim 1 wherein the 5-substituent is lower-alkoxyphenoxy.

3. A process according to claim 1 wherein the 5-substituent is lower-alkylphenoxy.

4. A process according to claim 1 wherein the 5-substituent is halophenoxy.

5. A process which comprises the step of converting an N acyl 1-halo-2-carbamyloxy-3-substituted propane wherein the nitrogen atom of the carbamyl group bears a hydrogen atom in addition to the acyl group and the 3-substituent is selected from the group consisting of phenoxy, lower-alkylphenoxy, lower-alkoxyphenoxy, halophenoxy and naphthyloxy, to a S-substituted-methyl-Z- oxazolidone wherein the S-substituent corresponds to the aforesaid 3-substituent and the nitrogen atom of the oxazolidine ring bears a hydrogen atom by reaction with an alkali metal hydroxide.

6. A process according to claim 5 where the S-substituent is lower-alkoxyphenoxy.

7. A process according to claim 5 wherein the S-substituent is lower-alkylphenoxy.

8. A process according to claim 5 wherein the 5-substituent is halophenoxy.

(References on following page) Refaremes fires] in the file of this patent UNTTED STATES PATENTS OTHER REFERENCES Wagner et 21.: Synthetic Organic Chemistry, (New York, 1953), pages 566-8, 576, 646-7 and 678-9. Lely 1959 Groggins: Unit Prscesses 111 Organic Synthesis (New Berger Apr. 28, 1959 5 YOi-k: 1g47) Lunsfcrd y 21, 1959 Adams et 21.: I. Am. Chem. 800., volume 45, pages Walles et a1 Dec. 29, 1959 785-7 (1923). g -k l 3 19 2 Elderfield: Heterocyciic Compounds volume 5, page 398 (1957). FOREIGN PATENTS 19 Chabrier et 211.: Chem. Abstracts, volume 49, C01.

Gemany 1927 Scatt et a1: Chem. Abstracts, Vol. 51, C01. 15227 Gsrmany June 21, 1961 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No 3 ,l68 ,525 7 February 2 1965 Manuel Mo Baizer It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent showld read as corrected below a Column 1, line 21, for "oXa" read oxazolldones in which the nitrogen atom of the oxalines 35 and 36, for "cycylizing" read cyclizing column 2, line 61, for

" (o-metho xyphenoxymethyl(dioXolone" read (0-methoxyphenoxymethyl) dioxolone line 71, for "thioyl" read thionyl column 3 line 29 after "methyl", in italics, insert a closing parenthesis column 4 line 34, for 'degress" read degrees Signed and sealed this 6th day of July 1965 (SEAL) Attest:

ERNEST W, SWIDER' EDWARD J BRENNER Attesting Officer Commissioner of Patents 

1. A PROCESS FOR PREPARING A 5-SUBSTITUTED-METHYL-2OXAZOLIDONE HAVING A HYDROGEN ATOM ATTACHED TO THE NITROGEN ATOM OF THE OXAZOLIDINE RING, WHEREIN THE 5-SUBSTITUENT IS SELECTED FROM THE GROUP CONSISTING OF PHENOXY, LOWER-ALKYLPHENOXY, LOWER-ALKOXYPHENOXY, HALOPHENOXY AND NAPHTHYLOXY, WHICH INCLUDES THE STEPS: REACTING WITH AN ACYLATING AGENT SELECTED FROM THE GROUP CONSISTING OF LOWER-ALKANOIC ACID CHLORIDES AND ANHYDRIDES, A 3-SUBSTITUTED-1-CHLORO-2-CARBAMYLOXY-PROPANE WHOSE CARBAMYL NITROGEN ATOM IS UNSUBSTITUTED, WHEREIN THE 3-SUBSTITUENT CORRESPONDS TO THE AFORESAID 5-SUBSTITUENT, TO PRODUCE THE CORRESPONDING 3-SUBSTITUTED-1-CHLORO-2-(N-ACYLCARBAMYLOXY)-PROPANE; AND TREATING SAID ACYLCARBAMLOXY-PROPANE WITH AN ALKALI METAL HYDROXIDE TO YIELD THE AFORESAID 5SUBSTITUTED-METHYL-2-OXAZOLIDONE.
 5. A PROCESS WHICH COMPRISES THE STEP OF CONVERTING AN N - ACYL - 1-HALO-2-CARBAMLOXY-3-SUBSTITUTED PROPANE WHEREIN THE NITROGEN ATOM OF THE CARBAMYL GROUP BEARS A HYDROGEN ATOM IN ADDITION TO THE ACYL GROUP AND THE 3-SUBSTITUENT IS SELECTED FROM THE GROUP CONSISTING OF PHENOXY, LOWER-ALKYLPHENOXY, LOWER-ALKOXYPHENOXY, HALOPHENOXY AND NAPHTHYLOXY, TO A 5-SUBSTITUTED-METHYL-2OXAZOLIDONE WHEREIN THE 5-SUBSTITUENT CORRESPONDS TO THE AFORESAID 3-SUBSTITUENT AND THE NITROGEN ATOM OF THE OXAZOLIDONE RING BEARS A HYDROGEN ATOM BY REACTION WITH AN ALKALI METAL HYDROXIDE. 